Question

A frustum of a cone is formed by cutting a right circular cone. The ratio of the

smaller and the bigger radius of the frustum is 1:2. The height is equal to the

bigger radius ‘R’. Which of the following is the volume of the full cone from which

the frustum was cut out?​

Answer 1

Answer:

please mark me brainalist

Step-by-step explanation:

Curved Surface area of a frustum of a cone =πl(r

1

+r

2

) where l is the slant height =

h

2

+(r

1

−r

2

)

2

h is the height.

r

1

and r

2

are the radii of the lower and upper ends of a frustum of a cone.

So, l=

16

2

+(20−8)

2

∴l=20cm

Hence, Curved surface area of this frustum of a cone =π×20×(20+8)=560πcm

2

Answer 2

Answer:

Curved Surface area of a frustum of a cone =πl(r1 + r2 ) where l is the slant height =

$\sqrt{h {}^{2} + (r1 - r2) {}^{2} } h \: is \: the \: height.$

r1 and r2 are the radii of the lower and upper ends of a frustum of a cone.

So,

$l = \sqrt{16 {}^{2} + (20 - 8) {}^{2} }$

∴ l = 20cm.

Hence, Curved surface area of this frustum of a cone

$= pi \: \times 20 \times (20 + 8) = 560pi \: cm {}^{2} .$